Computer simulation models are becoming increasingly popular for predicting soil loss through qua... more Computer simulation models are becoming increasingly popular for predicting soil loss through quantification of the processes of detachment, transport and deposition of eroded soils. To assess the effects of different management practices on soil erosion and to select the best management practices, application of models (especially process-oriented models) and their validation is considered a positive step. In this research, the Rangeland Hydrology and Erosion Model (RHEM) was evaluated using soil erosion measuring plots and the recorded rain in Sangane Research Station, Khorasan Razavi Province of Iran. The model was run and the predicted runoff and sediment yield values were compared with measured runoff and sediment yield values. Then sensitivity analysis and calibration were done on sensitive parameters and model was run with calibrated parameters. In the calibration period the, the model efficiency (ENS) values and the coefficient of determination (r 2 ) were 0.92 and 0.95 for ...
Time of concentration (TC) of surface flow in watersheds depends on the coupled response of hills... more Time of concentration (TC) of surface flow in watersheds depends on the coupled response of hillslopes and stream networks. The important point in this background is to study the effects of the geometry and the shape of complex hillslopes on the time of concentration considering the degree of flow convergence (convergent, parallel or divergent) as well as the profile curvature (concave, straight or convex). In this research, the shape factor of complex hillslopes as introduced by Agnese et al. (2007) is generalized and linked to the TC. A new model for calculating TC of complex hillslopes is presented, which depends on the plan shape, the type and degree of profile curvature, the Manning roughness coefficient, the flow regime, the length, the average slope, and the excess rainfall intensity. The presented model was compared to that proposed by Singh and Agiralioglu (1981a,b) and Agiralioglu (1985). Moreover, the results of laboratory experiments on the travel time of surface flow of...
The hydrologic response of a hillslope to rainfall involves a complex, transient saturated-unsatu... more The hydrologic response of a hillslope to rainfall involves a complex, transient saturated-unsaturated interaction that usually leads to a water table rise. An increase of saturated groundwater flow can act as the triggering mechanism for slope failure. To account for the three-dimensional hillslope shape in which the groundwater flow and storage processes take place, simple (low-dimensional) but physically realistic models that represent hydrological processes at the hillslope scales are needed for reliable simulation of ...
In this study, the process-based watershed model, Soil and Water Assessment Tool (SWAT), was used... more In this study, the process-based watershed model, Soil and Water Assessment Tool (SWAT), was used for simulating hydrology and sediment transport in the Gharesou watershed and for identifying critical areas of soil erosion and water pollution. After model calibration and uncertainty analysis using SUFI-2 (Sequential Uncertainty Fitting, ver. 2) method, the outputs of the calibrated model were used for assessing critical sediment source areas. Three pollution quantifying indices including a Load Impact Index (LII), a Concentration Impact Index (CII), and a load per nit area impact index (LUII), were computed based on the model outputs. The results indicated that despite lack and uncertainty of available data, SWAT model performance in simulating sediment transport in Gharesou watershed is quite acceptable. During calibration, the simulated monthly sediment loads matched the observed values with a Nash-Sutcliffe coefficient of 0.24 and PBIAS of - 17%. The values for validation period ...
Groundwater quality management is the most important issue in many arid and semi-arid countries, ... more Groundwater quality management is the most important issue in many arid and semi-arid countries, including Iran.Artificial neural network (ANN) has an extensive range of applications in water resources management. In this study,artificial neural network was developed using MATLAB R2013 software package, and Cl, EC, SO4 and NO3 qualitativeparameters were estimated and compared with the measured values, in order to evaluate the influence of key inputparameters. The number of neurons in the hidden layer was obtained by the trial-and-error method. For this purpose, datafrom 260 water samples of 13 wells in Bahabad plain were collected during 2003- 2013. The results show that theperformance of ANN model was more accurate for Cl (R=0.96), EC(R=0.98), and SO4(R=0.95), using back-propagationalgorithms according to the best chosen input parameters. It was observed that the use of ANN model for NO3 was notvery accurate, perhaps this was because of the different water sources or the impact of ...
Estimation of the design flood flow for hydraulic structures is often performed adjusting probabi... more Estimation of the design flood flow for hydraulic structures is often performed adjusting probabilistic models to daily mean flow series. In most of the cases this may cause an underdesign of the structure capacity with possible risks of failure, because instantaneous peak flows may be considerably larger than daily averages. Therefore estimation of the instantaneous peak flows is often needed for simulation of the reservoir operation based on the hydraulic characteristics of the structures and the operation rules. Because there is often a lack of instantaneous flow data at a given site of interest, the peak flow has to be estimated. This paper develops a new ANN based method to estimate the instantaneous peak flow from mean daily flow data. This methodology was successfully applied to a series of flow information from gauging stations in Iran, with important improvements compared to the traditional methods available in the literature.
Most of Iran areas have been located in arid and semi arid climates. Water resource scarcity is o... more Most of Iran areas have been located in arid and semi arid climates. Water resource scarcity is one of the woblems that has been attended by experts, decision makers and managers of the country. With respect to occurring droughts in recent years, proper management of existing water resources and also achieving to the better solution for their usage are essential. One of the ways that a large volume of water can be losses through the land surface is evapotranspiration (ET) as it has an important role in water resource !}lanagement. ET of each region is generally affected by different climatic parameters as well as its geographical attributes. To have a proper management of the ET, as a great water losing way, it seems to be necessary to know and study the ET and its effective parameters in each region. Sensitivity analysis is always known as one of these approaches. This approach seeks to attribute uncertain output to specific input parameters. The input parameters are varied in turn...
Global Journal of Environmental Science and Management, 2016
Erosion plots were selected for characterizing the effects of main natural factors on runoff and ... more Erosion plots were selected for characterizing the effects of main natural factors on runoff and soil loss in a semi-arid region. These erosion plots with an area of 40 m 2 are located in the Kakhk experimental watershed in Gonabad County of Khorasan-e Razave Province in the north-eastern Iran. Data acquired from 2008 to 2015 include slope, aspect, soil texture and land covers (canopy and litter) factors that were selected as main natural factors and it was tried to determine the effects of these factors on runoff and soil loss amount. In the next stage, it was focused on evaluation of the effects of land covers on runoff generation and soil loss in more details. For this purpose, in each class of the mentioned factors, the relationship between land covers and runoff and soil loss was analysed. The maximum of runoff and soil loss were occurred at E site with the amount of 15.6 mm and 140 g/m 2 respectively. Results showed that soil loss and runoff have decreased where the amounts of...
Undesirable effects of droughts on the agricultural and economical sectors and especially on the ... more Undesirable effects of droughts on the agricultural and economical sectors and especially on the natural resources are intense. Different methods have been presented to predict the main factors of drought such as precipitation and during the recent decades some new computer based models have been developed for drought prediction. In most cases these models have presented quite satisfactory results. Decision tree, as one of these models, produces rules based on evaluation of the parameters from portion (component) to the whole, and finally reaches understandable knowledge from the existing statistical data. In this research, decision tree model has been used as a data mining method to predict precipitation and evaluation of drought in Yazd synoptic meteorological station. Simulations were carried out in four different conditions. Related variables including previous monthly precipitation, mean temperature, maximum temperature, humidity, wind speed, wind direction, and evaporation wer...
D’Odorico & Fagherazzi (2003) have proposed a probabilistic model of rainfall-triggered shallow l... more D’Odorico & Fagherazzi (2003) have proposed a probabilistic model of rainfall-triggered shallow landslides in hollows. Their model describes the long-term evolution of colluvial deposits through a probabilistic soil mass balance at a point. The model accounts for hollow infilling, expressed as a deterministic function of the deposit thickness, and soil erosion by shallow landslides, modeled as a time-dependent stochastic point process related to the occurrence of triggering precipitation events. Further building blocks of the model are: an infinite-slope stability analysis; a steady-state kinematic wave model of hollow groundwater hydrology; and a statistical model relating intensity, duration, and frequency of extreme precipitation. The authors provide an analytical solution to their model under the simplifying assumption that the occurrence rate of landslide-triggering rain events is independent of the colluvial deposit thickness. We present an exact solution to the stochastic lan...
Prediction of climatic variables on a local scale by General Circulation Models of the atmosphere... more Prediction of climatic variables on a local scale by General Circulation Models of the atmosphere is impossible because the models have large-scale network of resolution. Therefore, downscaling methods are used to solve this problem. Since the climate change phenomenon can affect different systems such as, water resources, agriculture, environment, industry and economy as well, Selection of the most suitable downscaling method is very important. This study aims to evaluate performance of Change-Factor (CF) and LARS-WG downscaling methods in prediction of future climate variability of the Azam River Watershed, located in Yazd Province, Iran, for the period of 2010-2039. For this purpose, the CGCM3-AR4 model under the A2 emission scenario and also two methods of downscaling including statistical (LARS-WG) and proportional (CF) approaches were applied. The results showed increasing of temperature by both downscaling methods in the Azam River watershed in the future. Average temperature...
Computer simulation models are becoming increasingly popular for predicting soil loss through qua... more Computer simulation models are becoming increasingly popular for predicting soil loss through quantification of the processes of detachment, transport and deposition of eroded soils. To assess the effects of different management practices on soil erosion and to select the best management practices, application of models (especially process-oriented models) and their validation is considered a positive step. In this research, the Rangeland Hydrology and Erosion Model (RHEM) was evaluated using soil erosion measuring plots and the recorded rain in Sangane Research Station, Khorasan Razavi Province of Iran. The model was run and the predicted runoff and sediment yield values were compared with measured runoff and sediment yield values. Then sensitivity analysis and calibration were done on sensitive parameters and model was run with calibrated parameters. In the calibration period the, the model efficiency (ENS) values and the coefficient of determination (r 2 ) were 0.92 and 0.95 for ...
Time of concentration (TC) of surface flow in watersheds depends on the coupled response of hills... more Time of concentration (TC) of surface flow in watersheds depends on the coupled response of hillslopes and stream networks. The important point in this background is to study the effects of the geometry and the shape of complex hillslopes on the time of concentration considering the degree of flow convergence (convergent, parallel or divergent) as well as the profile curvature (concave, straight or convex). In this research, the shape factor of complex hillslopes as introduced by Agnese et al. (2007) is generalized and linked to the TC. A new model for calculating TC of complex hillslopes is presented, which depends on the plan shape, the type and degree of profile curvature, the Manning roughness coefficient, the flow regime, the length, the average slope, and the excess rainfall intensity. The presented model was compared to that proposed by Singh and Agiralioglu (1981a,b) and Agiralioglu (1985). Moreover, the results of laboratory experiments on the travel time of surface flow of...
The hydrologic response of a hillslope to rainfall involves a complex, transient saturated-unsatu... more The hydrologic response of a hillslope to rainfall involves a complex, transient saturated-unsaturated interaction that usually leads to a water table rise. An increase of saturated groundwater flow can act as the triggering mechanism for slope failure. To account for the three-dimensional hillslope shape in which the groundwater flow and storage processes take place, simple (low-dimensional) but physically realistic models that represent hydrological processes at the hillslope scales are needed for reliable simulation of ...
In this study, the process-based watershed model, Soil and Water Assessment Tool (SWAT), was used... more In this study, the process-based watershed model, Soil and Water Assessment Tool (SWAT), was used for simulating hydrology and sediment transport in the Gharesou watershed and for identifying critical areas of soil erosion and water pollution. After model calibration and uncertainty analysis using SUFI-2 (Sequential Uncertainty Fitting, ver. 2) method, the outputs of the calibrated model were used for assessing critical sediment source areas. Three pollution quantifying indices including a Load Impact Index (LII), a Concentration Impact Index (CII), and a load per nit area impact index (LUII), were computed based on the model outputs. The results indicated that despite lack and uncertainty of available data, SWAT model performance in simulating sediment transport in Gharesou watershed is quite acceptable. During calibration, the simulated monthly sediment loads matched the observed values with a Nash-Sutcliffe coefficient of 0.24 and PBIAS of - 17%. The values for validation period ...
Groundwater quality management is the most important issue in many arid and semi-arid countries, ... more Groundwater quality management is the most important issue in many arid and semi-arid countries, including Iran.Artificial neural network (ANN) has an extensive range of applications in water resources management. In this study,artificial neural network was developed using MATLAB R2013 software package, and Cl, EC, SO4 and NO3 qualitativeparameters were estimated and compared with the measured values, in order to evaluate the influence of key inputparameters. The number of neurons in the hidden layer was obtained by the trial-and-error method. For this purpose, datafrom 260 water samples of 13 wells in Bahabad plain were collected during 2003- 2013. The results show that theperformance of ANN model was more accurate for Cl (R=0.96), EC(R=0.98), and SO4(R=0.95), using back-propagationalgorithms according to the best chosen input parameters. It was observed that the use of ANN model for NO3 was notvery accurate, perhaps this was because of the different water sources or the impact of ...
Estimation of the design flood flow for hydraulic structures is often performed adjusting probabi... more Estimation of the design flood flow for hydraulic structures is often performed adjusting probabilistic models to daily mean flow series. In most of the cases this may cause an underdesign of the structure capacity with possible risks of failure, because instantaneous peak flows may be considerably larger than daily averages. Therefore estimation of the instantaneous peak flows is often needed for simulation of the reservoir operation based on the hydraulic characteristics of the structures and the operation rules. Because there is often a lack of instantaneous flow data at a given site of interest, the peak flow has to be estimated. This paper develops a new ANN based method to estimate the instantaneous peak flow from mean daily flow data. This methodology was successfully applied to a series of flow information from gauging stations in Iran, with important improvements compared to the traditional methods available in the literature.
Most of Iran areas have been located in arid and semi arid climates. Water resource scarcity is o... more Most of Iran areas have been located in arid and semi arid climates. Water resource scarcity is one of the woblems that has been attended by experts, decision makers and managers of the country. With respect to occurring droughts in recent years, proper management of existing water resources and also achieving to the better solution for their usage are essential. One of the ways that a large volume of water can be losses through the land surface is evapotranspiration (ET) as it has an important role in water resource !}lanagement. ET of each region is generally affected by different climatic parameters as well as its geographical attributes. To have a proper management of the ET, as a great water losing way, it seems to be necessary to know and study the ET and its effective parameters in each region. Sensitivity analysis is always known as one of these approaches. This approach seeks to attribute uncertain output to specific input parameters. The input parameters are varied in turn...
Global Journal of Environmental Science and Management, 2016
Erosion plots were selected for characterizing the effects of main natural factors on runoff and ... more Erosion plots were selected for characterizing the effects of main natural factors on runoff and soil loss in a semi-arid region. These erosion plots with an area of 40 m 2 are located in the Kakhk experimental watershed in Gonabad County of Khorasan-e Razave Province in the north-eastern Iran. Data acquired from 2008 to 2015 include slope, aspect, soil texture and land covers (canopy and litter) factors that were selected as main natural factors and it was tried to determine the effects of these factors on runoff and soil loss amount. In the next stage, it was focused on evaluation of the effects of land covers on runoff generation and soil loss in more details. For this purpose, in each class of the mentioned factors, the relationship between land covers and runoff and soil loss was analysed. The maximum of runoff and soil loss were occurred at E site with the amount of 15.6 mm and 140 g/m 2 respectively. Results showed that soil loss and runoff have decreased where the amounts of...
Undesirable effects of droughts on the agricultural and economical sectors and especially on the ... more Undesirable effects of droughts on the agricultural and economical sectors and especially on the natural resources are intense. Different methods have been presented to predict the main factors of drought such as precipitation and during the recent decades some new computer based models have been developed for drought prediction. In most cases these models have presented quite satisfactory results. Decision tree, as one of these models, produces rules based on evaluation of the parameters from portion (component) to the whole, and finally reaches understandable knowledge from the existing statistical data. In this research, decision tree model has been used as a data mining method to predict precipitation and evaluation of drought in Yazd synoptic meteorological station. Simulations were carried out in four different conditions. Related variables including previous monthly precipitation, mean temperature, maximum temperature, humidity, wind speed, wind direction, and evaporation wer...
D’Odorico & Fagherazzi (2003) have proposed a probabilistic model of rainfall-triggered shallow l... more D’Odorico & Fagherazzi (2003) have proposed a probabilistic model of rainfall-triggered shallow landslides in hollows. Their model describes the long-term evolution of colluvial deposits through a probabilistic soil mass balance at a point. The model accounts for hollow infilling, expressed as a deterministic function of the deposit thickness, and soil erosion by shallow landslides, modeled as a time-dependent stochastic point process related to the occurrence of triggering precipitation events. Further building blocks of the model are: an infinite-slope stability analysis; a steady-state kinematic wave model of hollow groundwater hydrology; and a statistical model relating intensity, duration, and frequency of extreme precipitation. The authors provide an analytical solution to their model under the simplifying assumption that the occurrence rate of landslide-triggering rain events is independent of the colluvial deposit thickness. We present an exact solution to the stochastic lan...
Prediction of climatic variables on a local scale by General Circulation Models of the atmosphere... more Prediction of climatic variables on a local scale by General Circulation Models of the atmosphere is impossible because the models have large-scale network of resolution. Therefore, downscaling methods are used to solve this problem. Since the climate change phenomenon can affect different systems such as, water resources, agriculture, environment, industry and economy as well, Selection of the most suitable downscaling method is very important. This study aims to evaluate performance of Change-Factor (CF) and LARS-WG downscaling methods in prediction of future climate variability of the Azam River Watershed, located in Yazd Province, Iran, for the period of 2010-2039. For this purpose, the CGCM3-AR4 model under the A2 emission scenario and also two methods of downscaling including statistical (LARS-WG) and proportional (CF) approaches were applied. The results showed increasing of temperature by both downscaling methods in the Azam River watershed in the future. Average temperature...
Uploads
Papers by Ali Talebi